Re: gEDA-user: Magnetic bike operation

[Rob Butts <r.butts2@xxxxxxxxx>]

   So I'd lke to make this programable; therefore, in lieu of a permanent
   magnet and bringing it closer to the disk to increase the resistance I
   could use an electromagnet and increase the magnetic field?

   On Mon, Mar 29, 2010 at 11:39 AM, David C. Kerber
   <[1]dkerber@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

     Just attach a disk of some conductive material to the axle of the
     thing you want to brake, and mount a strong permanent magnet so that
     it's near but not touching the flat surface of the disk.  I think a
     C-shaped magnet with the opening just big enough to clear the disk
     would work even better, but it's not required.  I believe my trainer
     uses two magnets, one on each side of the disk, facing each other.
     If you're putting any significant continuous load on it, you will
     need some cooling; my trainer's load box get pretty warm after I've
     been using it for 20 minutes or so, and it has fan blades to drive
     air flow through it whenever it's turning.

   > -----Original Message-----
   > From: [2]geda-user-bounces@xxxxxxxxxxxxxx
   > [mailto:[3]geda-user-bounces@xxxxxxxxxxxxxx] On Behalf Of Rob Butts

   > Sent: Monday, March 29, 2010 11:15 AM
   > To: gEDA user mailing list

   > Subject: Re: gEDA-user: Magnetic bike operation
   >
   > I've read about the eddy current breaks but it's still not
   > clear to me how to construct one.  The wikipedia talks about
   > a rotor connected to a spinnning coil.  I would think the
   > rotor would spin inside a coil.  Then wikipedia talks about
   > using electromagnets and varying the breaking force by
   > varying the magnetic field.
   >
   > On Sun, Mar 28, 2010 at 8:03 PM, David C. Kerber <
   > [4]dkerber@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
   >
   > > My bicycle trainer uses an eddy current brake; there are no wires
   > > anywhere in the load; just a ventilated disk and a magnet
   > that I can
   > > move closer or further away from the disk by turning an
   > adjustment dial.
   > >
   > > D
   > >
   > >
   > >
   > > > -----Original Message-----
   > > > From: [5]geda-user-bounces@xxxxxxxxxxxxxx
   > > > [mailto:[6]geda-user-bounces@xxxxxxxxxxxxxx] On Behalf Of Rob
   Butts
   > > > Sent: Saturday, March 27, 2010 4:29 PM
   > > > To: gEDA user mailing list
   > >  > Subject: gEDA-user: Magnetic bike operation
   > > >
   > > > I'm having a debate with an ee friend about how the magnetic
   > > > resistance works on an excersice bike.
   > > >
   > > > It occurred to me this would be the best place to solve it.
   > > >
   > > > Does anyone know if it is simply an electro-magnet close
   > to a metal
   > > > wheel where the stronger the magnetic field the stronger the
   > > > resistance?  Or is it alternating magnets in a flywheel type
   > > > configuration with a toriodal coil surrounding the flywheel and a
   > > > variable resistance in the coil circuit resists the
   > induced current
   > > > providing the resistance to user who would be spinning
   > the flywheel?
   > > > (Sorry if I didn't describe that well).
   > > >
   > > > Or is it something completely different?
   > > >
   > > > Thanks
   > > >
   > >
   > >
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   > >
   >
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References

   1. mailto:dkerber@xxxxxxxxxxxxxxxxxxxxxxxxxx
   2. mailto:geda-user-bounces@xxxxxxxxxxxxxx
   3. mailto:geda-user-bounces@xxxxxxxxxxxxxx
   4. mailto:dkerber@xxxxxxxxxxxxxxxxxxxxxxxxxx
   5. mailto:geda-user-bounces@xxxxxxxxxxxxxx
   6. mailto:geda-user-bounces@xxxxxxxxxxxxxx
   7. mailto:geda-user@xxxxxxxxxxxxxx
   8. http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
   9. mailto:geda-user@xxxxxxxxxxxxxx
  10. http://www.seul.org/cgi-bin/mailman/listinfo/geda-user


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